Features of respiration biomechanics at mechanical pressure-controlled helium-oxygen ventilation

Aim. To study the dynamics of inspiratory pressure and volume in two versions of the experiment - mechanical pressure-controlled air-oxygen and helium-oxygen ventilation in the models of «healthy lung», «chronic obstructive pulmonary disease», «acute respiratory distress syndrome».

Methods. Inspiratory pressure and tidal volume were recorded during 10 respiratory cycles at each predetermined level from 5 to 20 cm H2O with a step of 5 cm H2O. TestСhest® was used as a model of the lungs which allows simulating normal function and some pathological states of the lungs sucj as COPD and ARDS.

Results. In the model of «healthy lung» inspiratory pressure in the application of air-oxygen mixture and helium-oxygen mixture was: at level 5 cm H2O - 6.4 (6.26; 6.50) and 7.17 (6.94; 7.17) cm H2O; 10 cm H2O - 11.31 (11.2; 11.43) and 12.11 (12.11; 12.27) cm H2O; 15 cm H2O - 16.8 (16.8; 17.03) and 15.24 (15.07; 15.24) cm H2O and at the level of 20 cm H2O - 18.83 (18.65; 19.04) and 21.52 (21.34; 21.67) cm H2O. At this, the respiratory volumes were 262.1 ml and 280.3 ml at the level 5 cm H2O; 541.8 ml and 577.9 ml at 10 cm H2O, 836.9 ml and 925.9 ml at 15 cm H2O; 1109 ml and 1265 ml at 20 cm H2O. In other studied models the inspiratory pressure and respiratory volume were also determined. Comparison of indicators revealed a statistically significant increase of the studied parameters in the simulated pathological conditions.

Conclusion. Pressure-controlled use of helium-oxygen mixture in the simulation of normal breathing mechanics, acute respiratory distress syndrome and chronic obstructive pulmonary disease is accompanied by a statistically significant increase in inspiratory pressure in the airways and inspiratory volume.